The decline of sectorial components of the world's energy intensity

The world's primary energy consumption in the last 40 years has been increasing at 2.2%/year while GDP growth has been 3.4%/years over the same period. The decline of the energy intensity (I=E/GDP) has been, therefore, of 1.2%/year. In order to reduce the world's consumption growth proposal have been made to reduce the world's energy intensity by 40% by 2030 which corresponds to a reduction of 2.5%/year, roughly the double of the historical decline. Our analysis shoes that such goal could only be achieved by an unprecedented reduction of the energy intensity of “services” (which represent less than half the world energy consumption) since energy intensity of industry has remained practically constant in the last 40 years.     

Numerical simulation of turbulent natural convection of nanofluid with thermal radiation inside a tall enclosure under the influence of magnetohydrodynamic

In the present study, the natural convective heat transfer in the turbulent flow of water/CuO nanofluid with volumetric radiation and magnetic field inside a tall enclosure has been numerically investigated. The thermophysical properties of nanofluid have been considered variable with temperature and the effects of Brownian motion of nanoparticles have been considered. The main objective of this work is an investigation of the effect of using water/CuO nanofluid and presence of magnetic field on turbulent natural convection in three types of enclosures (vertical, inclined, and horizontal) by considering the volumetric radiation. The governing equations on turbulent flow domain under the influence of the magnetic field and by considering the combination of volumetric radiation and natural convection have been solved by a coupled algorithm. For validating the present research, a comparison has been carried out with the laminar natural convection flow under the influence of the magnetic field and radiation effects and also, the natural turbulent convection flow of previous studies and a proper coincidence has been achieved. The results indicated that by increasing volume fraction and Hartmann number the average Nusselt number enhances and reduces, respectively. By adding 1% CuO nanoparticles to the base fluid, heat transfer improves from 10.59% to 17.05%. However, by increasing the volume fraction from 1% to 4%, heat transfer improves from 1.35% to 4.90%. By increasing Hartmann number from 0 to 600, heat transfer reduces from 9.29% to 22.07%. Also, the results show that the ratio of deviation angle of the enclosure to the horizontal surface has considerable effects on heat transfer performance. Therefore, in similar conditions, the inclined enclosure with a deviation angle of 45° compared to the vertical and horizontal enclosure has better thermal performance.     

Experimental study of effect of an inner thermal curtain in evaporative cooling system of a cascade greenhouse

In this paper experimental study has been carried out in a cascade greenhouse with inner thermal curtain to see the effect of thermal curtain. A thermal model has also been developed to predict the air temperature in a cascade greenhouse. The fan-pad system has been used for evaporative cooling and an inner thermal curtain has been used to divide the greenhouse in two zones. Experiments have been conducted in hot summer conditions at Solar Energy Park, IIT Delhi, New Delhi, India for empty greenhouse. Statistical analysis has been carried out to validate the agreement of experimental observations with predicted values. The values of the root mean square percent deviation and coefficient of correlation has been found out 9.0%, 0.90; 5.0%, 0.95 and 7.0%, 0.97 for April, May and June in case of evaporative cooling without curtain in greenhouse-2. The degree of freedom for the experimental work is 10.0. It is found that the use of evaporative cooling with a thermal curtain reduces the temperature of greenhouse by 5 °C and 8 °C in the second zone of greenhouse-1 and 2 in comparison to greenhouse without curtain in May.     

Experimental investigation of a solar energy heating system under the climatic conditions of Edirne

Seasonal storage of solar energy to supply the heat requirement of buildings in Edirne (41°39′54″N) has been examined experimentally. Solar energy has been stored in a cylindrical underground storage unit. Measurement values have been recorded per hour by means of a computerized recorder between July 2005 and May 2006. Monthly average temperature values of the heat storage unit and the surrounding ground have been calculated through the measurement results. The transient heat transfer which takes place between the heat storage unit and the surrounding ground has been calculated by means of the QuickField finite-element analysis program. It has been determined that the most significant deviations between the theoretical and the experimental temperature values turn out to be in question during the heating period. The annual solar fraction of the solar energy heating system has been determined as 53% for space heating and 85% for domestic water heating.     

Degradation analysis of a heavy-duty gas turbine engine under full and part load conditions

This paper describes the degradation analysis and the performance diagnostics of the gas-turbine (GT) cycle of a combined cycle power plant (CCPP). Three different operating loads, which are 100%, 75%, and 50%, were tested at different ambient conditions, namely, temperature, pressure, and humidity. First, a degradation model to simulate the GT performance with these various operating loads and conditions has been developed. It is then demonstrated how this degradation affects the GT and its components. The degradation analysis has been performed on 2500 readings obtained during 2 years of operation. After applying the load determining criteria, 60 readings were obtained to represent the full load operation and 40 reading points for each part-load operation. The degradation analysis has been carried out on the basis of actual data obtained from a CCPP; this differentiates this study from the others in the same area. Based on the commissioning test performance of the GT cycle, the model has been validated. The results show that the rate of degradation increases dramatically as the load increases. Moreover, the degradation rate also increases with an increase in the ambient air temperature. However, the degradation rate for the various studied parameters, namely, polytropic efficiencies, GT exhaust mass flow rate, and the overall GT efficiency, has been found to decrease with time. The maximum degradation percentage has been estimated to be −1.71% at full load conditions in comparison with −1.33% and −1.16% at 75% and 50% load, respectively.     

Computed effects of tip clearance on performance of impulse turbine for wave energy conversion

This paper depicts numerical analysis on Impulse turbine with fixed guide vanes for wave energy conversion. From the previous investigations, it is found that one of the reasons for the mismatch between computed and experimental data is due to neglecting tip clearance ef fect. Hence, a 3-D model with tip clearance has been generated to predict the internal flow and performance of the turbine. As a result, it is found that the comparison between computed and experimental data is good, quantitatively and qualitatively. Computation has been carried out for various tip clearances to understand the physics of tip leakage flow and effect of tip clearance on performance of such unconventional turbine. It is predicted that the turbine with 0.25% tip clearance performs almost similar to the case of without tip clearance for the entire flow coefficients. The designed value of 1% tip clearance has been validated numerically and computed that the efficiency of the turbine has been reduced around 4%, due to tip clearance flow at higher flow coefficients.     

Optimisation of a solid oxide fuel cell reformer using surrogate modelling,design of experiments and computational fluid dynamics

The present paper proposes a trio approach including surrogate modelling, design of experiments and computational fluid dynamics. An experimentally validated 3D continuum model has been used in the aid to optimise the performance, weight and the associated manufacturing costs of a plate type pre-reformer. The effect of plate number, plate porosity, wire mesh porosity and alternative materials on the pre-reformer performance has been studied in detail using a D-optimal experimental design plan and computational fluid dynamics. Multi-regression analyses depict that the number of reformer plates has the greatest potential for optimisation. A surrogate model has been derived and employed to perform rapid process and design optimisations. Results show that the methane reforming can be 40% increased by reducing the pre-reformer plate number to half of the actual value. A mass reduction of 50%, associated with a saving of 50% may be enabled. The surrogate model is proven to be a powerful tool to aid in reduced physical prototype costs and product development time.     

油包水钻井液研究与应用

与水基钻井液相比,由于油基钻井液具有抗高温、抗盐钙侵、有利于井壁稳定、润滑性好和保护油气层等优点,成为钻遇深井、大斜度定向井、水平井和各种复杂地层的首选体系。油包水钻井液具有油基钻井液的优点。针对非常规油气藏及强水敏、易坍塌地层钻井的需要,研制了油包水钻井液,优化了钻井液配方:基液(油水体积比为8∶2)+3%主乳化剂+3%辅乳化剂+3%有机土+4%降滤失剂+3%的CaO+重晶石。室内评价结果表明,该油包水钻井液具有良好的流变性、悬浮稳定性、润滑性、乳液稳定性和抗污染能力。同时,完善了现场施工工艺,并在中原、新疆、西南等现场应用了7口井。应用证明,油包水钻井液稳定性好,破乳电压大于600V,抗污染、抗温能力强,遭受20%的水和岩屑污染后,钻井液性能稳定,易于维护处理;且钻井过程中井壁稳定,定向施工顺利,减少井下复杂,平均井径扩大率小于5%。该钻井液配制工艺简单,可以回收利用,满足页岩气水平井、易塌地层钻进的需要。     

Experimental validation of glazed hybrid micro-channel solar cell thermal tile

In this communication, an attempt has been made to evaluate the theoretical performance of a glazed hybrid micro-channel solar cell thermal (MCSCT) tile. Experiment has been performed in indoor condition and it has been observed that there is good agreement between theoretical and experimental values with correlation coefficient and root mean square percentage deviation in range of 0.995–0.998 and 3.21–4.50 respectively. Effect of design parameters on different combination (series and parallel) of glazed hybrid MCSCT tile for Srinagar climatic condition, India has also been evaluated. The theoretical results of glazed hybrid micro-channel photovoltaic thermal (MCPVT) module for 75 W_p have been compared with the result of single channel photovoltaic thermal (SCPVT) module. The average value of electrical and thermal efficiency of glazed hybrid MCPVT module are 14.7% and 10.8% respectively which is significantly higher than SCPVT module. The overall annual exergy efficiency based on second law of thermodynamics has also been evaluated at different mass flow rate for glazed hybrid MCPVT module for Srinagar climatic condition. It has been observed that maximum overall exergy efficiency is 20.28% at 0.000108 kg/s mass flow rate.     

Analysis of parameters affecting the performance of gas turbines and combined cycle plants with vapor absorption inlet air cooling

The integration of an aqua‐ammonia inlet air‐cooling scheme to a cooled gas turbine‐based combined cycle has been analyzed. The heat energy of the exhaust gas prior to the exit of the heat recovery steam generator has been chosen to power the inlet air‐cooling system. Dual pressure reheat heat recovery steam generator is chosen as the combined cycle configuration. Air film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor–pressure ratio, compressor inlet temperature, turbine inlet temperature, ambient relative humidity, and ambient temperature on performance parameters of plants has been carried out. It has been observed that vapor absorption inlet air cooling improves the efficiency of gas turbine by upto 7.48% and specific work by more than 18%, respectively. However, on the adoption of this scheme for combined cycles, the plant efficiency has been observed to be adversely affected, although the addition of absorption inlet air cooling results in an increase in plant output by more than 7%. The optimum value of compressor inlet temperature for maximum specific work output has been observed to be 25 °C for the chosen set of conditions. Further reduction of compressor inlet temperature below this optimum value has been observed to adversely affect plant efficiency. Copyright © 2013 John Wiley & Sons, Ltd.     

Performance,emission and combustion characteristics of a variable compression ratio engine using methyl esters of waste cooking oil and diesel blends

The performance, emission and combustion characteristics of a single cylinder four stroke variable compression ratio multi fuel engine when fueled with waste cooking oil methyl ester and its 20%, 40%, 60% and 80% blends with diesel (on a volume basis) are investigated and compared with standard diesel. The suitability of waste cooking oil methyl ester as a biofuel has been established in this study. Bio diesel produced from waste sun flower oil by transesterification process has been used in this study. Experiment has been conducted at a fixed engine speed of 1500 rpm, 50% load and at compression ratios of 18:1, 19:1, 20:1, 21:1 and 22:1. The impact of compression ratio on fuel consumption, combustion pressures and exhaust gas emissions has been investigated and presented. Optimum compression ratio which gives best performance has been identified. The results indicate longer ignition delay, maximum rate of pressure rise, lower heat release rate and higher mass fraction burnt at higher compression ratio for waste cooking oil methyl ester when compared to that of diesel. The brake thermal efficiency at 50% load for waste cooking oil methyl ester blends and diesel has been calculated and the blend B40 is found to give maximum thermal efficiency. The blends when used as fuel results in reduction of carbon monoxide, hydrocarbon and increase in nitrogen oxides emissions.     

Effects of changes in the UK energy-demand and environmental legislation on atmospheric pollution by oxides of nitrogen and black smoke

It has been demonstrated that the combustion of fossil fuels accounts for 95% of oxides of nitrogen and 90% of black-smoke emissions to the atmosphere over the 1970–1994 period. The study has shown that the overall NO_x emissions, over this period, have decreased by a modest 5%. Only the transport sector is seen to have increased its emission of NO_x. In contrast, black-smoke emissions are shown to have plummeted by 60% over this period. The overwhelming reason for this has been the decline in the demand for coal in the domestic sector. By 1994, over 50% of NO_x and black smoke was generated by road traffic. Petrol has been the major generator of NO_x and diesel the main producer of black smoke. Three pieces of legislation were brought into force to limit the emissions from power-generating plant and petrol-driven road traffic. It has been shown that significant reductions in NO_x emissions could be achieved in the power-generating sector by the increased use of CCGT and by adopting new energy technology.     

Performance of liquid convective diodes

A three year study has been conducted concerned with the operation of convective heat diodes—passive solar heating devices which absorb and accumulate solar energy and then transport heat preferentially to the inside of a building. The study has been carried out in Gliwice, Poland (latitude 50° north, longitude 19° east), in a strongly industrialized region with a considerable level of air pollution.A module was built that consisted of four overlapping thermal diodes made of plastics. It has been found that the diodes, which constitute only 6% of the test cell surface area, lead to energy savings as high as 37% compared with the reference cells. This corresponds to some 700 MJ of energy per 1 m² of the diode per year. Based on the experimental results, the parameters have been estimated which appear in the energy balance equations for the diodes. It has been concluded that it is the thermal resistance of the insulation between the accumulator of one diode and the collector of another which has a crucial effect upon the efficiency of the diode, and appropriate improvements to present-day diode designs have been suggested.     

Study on Friction Factor of Developing and Developed Laminnr Flow in Annular－Sector Ducts

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Energy conservation in large air-conditioned buildings: Use of evaporative roof cooling in hot and dry climates

Energy conservation potential of the evaporative roof cooling technique for a cinema house in a composite climate (characterized by Delhi) has been evaluated. Thermal loads due to heat conduction through the building envelope, the required ventilation and the occupants have been taken into account. Life-cycle-cost analysis has been employed to evaluate the cost effectiveness of this energy conservation technique. It is seen that evaporative cooling on the roof leads to a net saving of 14% in the initial investment and 17% in the annual cost.     

基于进出油腔结构优化的某型内啮合摆线机油泵的性能研究

在应用现有摆线机油泵进出油腔设计理论与半经验方法基础上,对某型内啮合摆线机油泵的进出油腔提出了改进方案,通过台架试验对机油泵性能进行了试验研究。试验结果表明,进出油腔结构优化后,机油泵的容积效率与总效率分别提升3%和2.9%。应用Pumplinx软件对机油泵进行仿真分析。结果表明,仿真结果与试验数据基本吻合,进、出油腔压力分布均匀,无气蚀,机油泵的优化改进满足设计要求。     

Integrated renewable energy systems for off grid rural electrification of remote area

The off grid electrification by utilizing Integrated Renewable Energy System (IRES) is proposed to satisfy the electrical and cooking needs of the seven-uneletrified villages in the Almora district of Uttarakhand state, India. Four different scenarios are considered during modeling and optimization of IRES to ensure reliability parameters such as energy index ratio (EIR) and expected energy not supplied (EENS). The optimum system reliability, total system cost and cost of energy (COE) have also been worked out by introducing the customer interruption cost (CIC). The four different renewable energy scenarios have been compared for the considered study area using the LINGO software version 10. The fourth renewable energy scenario accounting 44.99% micro hydropower (MHP), 30.07% biomass, 5.19% biogas and 4.16% solar energy along with the additional resources of wind (1.27%) and energy plantation (12.33%) has been found to be the best among the different options considered. Furthermore, the optimal reliability for the fourth IRES system has been found to be 0.95 EIR at the optimized cost of Rs 19.44 lacs with estimated COE of Rs 3.36 per kWh. The COE obtained using LINGO software and HOMER software has also been compared and briefly discussed for all the four scenarios. In order to verify feasibility and cost of system for different biomass fuel prices, a sensitivity analysis has also been carried out and it has been found that the fourth scenario is more sustainable than the other considered options.     

Evaluation of thermal efficiency and cost of high temperature solar heat from central receiver systems to use in hydrogen producing thermochemical processes

The thermal efficiency and cost evaluation of high temperature solar heat, for hydrogen producing processes, from central receiver systems has been carried out using the DELSOL2 code program developed at Sandia laboratories. The thermal performance and design optimization runs were performed for various locations with different levels of yearly direct insolation at normal incidence. The study has been carried out with an external vertical cylindrical receiver and for plant sizes ranging from 100 MW to 900 MW. It has been found that the overall thermal efficiency of the system varies from 51.3% to 56.1% and that the typical levelized thermal energy cost is in the range of 10 $ GJ⁻¹ for favorable locations. The results for small size systems have been verified using the CRS code developed at Ecole Polytechnique and the published results are in the literature. It has also been determined that for a system with a cavity type receiver, the levelized thermal energy cost is higher although the overall system thermal efficiency is improved.     

改善燃油物性降低车辆发动机有害排放和节能的试验研究

车辆尾气有害排放物所造成的环境污染日益严重，根据车辆发动机所用燃油特性，研究了一系列添加剂，由台架对比试验测出，该系列汽油添加剂可使尾气中的碳氢化合物降低３０．１％、一氧化碳降低２０％，柴油添加剂可使尾气中的烟度降低３０％，且节能效果良好。     

Effect of thermal boundary layer on radiative heat transfer from combustion plasma

The effect of thermal boundary layer on radiative heat transfer considering nongray nonisothermal plasma has been calculated for potassium seeded watergas combustion plasma. The effect of combustion species concentration and seed concentration on radiative flux under the equilibrium flow and frozen flow condition has been studied. It has been estimated that reduction in radiative flux due to cold boundary layer may be upto 25%.